Besides chemotaxis, C-X-C and C-C chemokines function as mediators in T-cell activation and in many lymphocyte biological responses. Detailed information about downstream signaling pathways is necessary to understand the role of chemokines in normal physiology and inflammation. We have built a focused cDNA chip containing 675 known genes that are expressed and secreted by lymphoid cells and participate in their growth, signal transduction, and apoptosis. In initial experiments using differential display analysis and commercial cDNA chips, Jurkat T cells expressing endogenous CXCR-4 and transfected with CXCR-3, were used to examine the ability of chemokine ligands to induce unique mRNA expression. We compared transfected cells treated with the C-X-C chemokines SDF-1-alpha that interacts via CXCR-4, and IP-10 that interacts via CXCR-3. Further experiments examined the effects of anti- CD3, TARC, 6Ckine, IL-8, MIP-3 alpha/LARC/Exodus, MIP-3- beta/ELC/Exodus-3, and HIV gp120 glycoprotein on mRNA expression by PBMC and purified T-cells. Using this approach, we have observed differences in gene expression by cells treated by different ligands that bind the same chemokine receptor. This focused microarray is also useful to define candidate genes for further study, and to identify informative experimental and clinical specimens prior to molecular profiling on the NIA 15K chip. - Microarray, chemokines, signaling, differential display, T cells, neuronal cells